As energy requirements continue to grow worldwide, there is an ever increasing need for additional power production processes. The current high efficiency method for power generation using natural gas fuel or distillate hydrocarbon fuels is the natural gas combined cycle (NGCC) system which comprises a Brayton Cycle gas turbine and a Rankine cycle steam system. The largest gas turbines commercially available are capable of a power output from the NGCC system in the range from about 450 MW (megawatts) to about 550 MW with lower heating value efficiencies in the range from about 56% to about 60% at ISO (International Organization for Standardization) conditions. Current single train units that employ a coal-fired boiler plus a steam generator are available that may have power outputs greater than 1,000 MW giving net electrical efficiencies of up to about 45% based on highest achievable steam conditions with current best boiler designs and materials. Nuclear reactors with a single steam turbine are available at power outputs greater than 1,000 MW.
In addition to the above, U.S. Patent Publication No. 2011/0179799 discloses a high pressure low pressure ratio power cycle using a carbonaceous or hydrocarbon fuel that is combusted the presence of a high concentration oxygen atmosphere and thus requires the provision of a highly pure oxygen source. The combustion products are cooled by a recycle of a high temperature, high pressure, and highly purified CO2 stream that has been heated against a turbine exhaust stream in a heat exchanger.
As seen above, existing and emerging technology in the field can require the use of multiple cycles and/or provision of highly purified materials for combustion. Accordingly, there remains a need for power systems using natural gas or distillate fuels combusted in air that can provide power outputs from a single train of up to 500 MW or even more.